Light emitting device, electrode structure, light emitting device package, and lighting system

ABSTRACT

Provided are a light emitting device, an electrode structure, a light emitting device package, and a lighting system. The light emitting device includes a conductive layer, an electrode, a light emitting structure layer disposed between the electrode and the conductive layer and comprising a first semiconductor layer, a second semiconductor layer, and an active layer between the first semiconductor layer and the second semiconductor layer, and a light guide layer between the first semiconductor layer and the electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(a) ofKorean Patent Application No. 10-2010-0025148 filed on Mar. 22, 2010,which is hereby incorporated by reference in its entirety.

BACKGROUND

Embodiment relate to a light emitting device, an electrode structure, alight emitting device package, and a lighting system.

Due to their physical and chemical characteristics, Group III-V nitridesemiconductors are being esteemed as core materials for light-emittingdevices such as light-emitting diodes (LEDs) and laser diodes (LDs).Each of the Group III-V nitride semiconductors is formed of asemiconductor material having a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1).

LEDs are a kind of semiconductor device that is used as a light sourceor uses the characteristics of compound semiconductors to convertelectricity into infrared rays or light, thereby receiving ortransmitting signals therebetween.

These semiconductor based LEDs or LDs are widely used in light-emittingdevices, and are applied as light sources for various products such askeypad light-emitting units of mobile phones, electric light panels, andillumination devices.

SUMMARY

Embodiments provide a new electrode structure and a light emittingdevice having the same.

Embodiments provide an electrode structure having improved lightextraction efficiency and a light emitting device having the same.

Embodiments provide a light emitting device having an electrodestructure including a light guide layer between a semiconductor layerand an electrode.

Embodiments provide a light emitting device package including a lightemitting device having new electrode structure and a lighting system.

An embodiment provides a light emitting device comprising: a conductivelayer; an electrode; a light emitting structure layer disposed betweenthe electrode and the conductive layer and comprising a firstsemiconductor layer, a second semiconductor layer, and an active layerbetween the first semiconductor layer and the second semiconductorlayer; and a light guide layer between the first semiconductor layer andthe electrode.

An embodiment provides a light emitting device comprising: a lightemitting structure layer including a first semiconductor layer, a secondsemiconductor layer, and an active layer between the first semiconductorlayer and the second semiconductor layer; an electrode contacting a topsurface of the first conductive layer; a light guide layer between theelectrode and the first semiconductor layer; and a plurality ofconductive layers under the second semiconductor layer, wherein an outersurface of the light guide layer non-contacts the electrode, and atleast portion of the outer surface is disposed under a region of theelectrode.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a first embodiment.

FIG. 2 is a plan view of FIG. 1.

FIG. 3 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a second embodiment.

FIG. 4 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a third embodiment.

FIG. 5 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a fourth embodiment.

FIG. 6 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a fifth embodiment.

FIG. 7 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a sixth embodiment.

FIGS. 8 to 10 are side-sectional views of an electrode structure on acompound semiconductor layer according seventh embodiment.

FIG. 11 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to an eighth embodiment.

FIGS. 12 to 21 are plan views of an electrode structure on a compoundsemiconductor layer according to a ninth embodiment.

FIG. 22 is a side-sectional view of a light emitting device according toa tenth embodiment.

FIG. 23 is a side-sectional view of a light emitting device according toan eleventh embodiment.

FIG. 24 is a side-sectional view of a light emitting device according toa twelfth embodiment.

FIG. 25 is a side-sectional view of a light emitting device according toa thirteenth embodiment.

FIG. 26 is a side-sectional view of a light emitting device according toa fourteenth embodiment.

FIG. 27 is a side-sectional view of a light emitting device packageaccording to a fifteenth embodiment.

FIG. 28 is a diagram illustrating a display device according to anembodiment;

FIG. 29 is a diagram illustrating another display device according to anembodiment; and

FIG. 30 is a diagram illustrating a lighting device according to anembodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the descriptions of embodiments, it will be understood that when alayer (or film), a region, a pattern, or a structure is referred to asbeing ‘on’ a substrate, a layer (or film), a region, a pad, or patterns,it can be directly on another layer or substrate, or intervening layersmay also be present. Further, it will be understood that when a layer isreferred to as being ‘under’ another layer, it can be directly underanother layer, and one or more intervening layers may also be present.Further, the reference about ‘on’ and ‘under’ each layer will be made onthe basis of drawings.

In the drawings, the thickness or size of each layer is exaggerated,omitted, or schematically illustrated for convenience in description andclarity. Also, the size of each element does not entirely reflect anactual size.

Hereinafter, embodiments will be described with reference toaccompanying drawings.

FIG. 1 is a side-sectional view of an electrode structure on a compoundsemiconductor layer according to a first embodiment, and FIG. 2 is aplan view of FIG. 1.

Referring to FIG. 1, an electrode 20 and a light guide layer 30 isdisposed on a compound semiconductor layer 10. The compoundsemiconductor layer 10 includes a compound semiconductor, e.g., a GroupIII-V compound semiconductor, and may be formed a semiconductor materialhaving a compositional formula of In_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1,0≦x+y≦1). For example, the compound semiconductor layer 10 may be formedof at least one selected from the group consisting of GaN, AlN, AlGaN,InGaN, InN, InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

The compound semiconductor layer 10 may be an N-type semiconductor layerdoped with an N-type dopant. The N-type dopant may include N-typedopants such as Si, Ge, Sn, Se, and Te. The compound semiconductor layer10 may be a P-type semiconductor layer doped with a P-type dopant. TheP-type dopant may include P-type dopants such as Mg, Zn, Ca, Sr, and Ba.The compound semiconductor layer 10 may be an undoped semiconductorlayer. The undoped semiconductor layer may be a low conductive layerwith respect to the n-type semiconductor.

The compound semiconductor layer 10 may have a single- or multi-layeredstructure. Also, the compound semiconductor layer 10 may include a lightemitting structure layer. For example, the compound semiconductor layer10 may have a structure in which an N-type semiconductor layer, anactive layer, and a P-type semiconductor layer are stacked in order froman upper layer, or a structure in which an N-type semiconductor layer,an active layer, a P-type semiconductor layer, and an N-typesemiconductor layer are stacked in order from an upper layer.

The electrode 20 may be a pad or an electrode having an arm or branchshape and connected to the pad. The electrode 20 may have a single- ormulti-layered structure and be formed of one of Cr, Ti, Al, In, Ta, Pd,Co, Ni, Si, Ge, Ag, Cu, and Au or combinations thereof. The electrode 20may be formed of one of the foregoing materials in consideration of anohmic contact, an adhesion, a reflective characteristic, and aconductive characteristic with respect to the compound semiconductorlayer 20.

When the electrode 20 is the pad, one or plurality of pads may beprovided. The plurality of pads may be electrically connected to eachother. When viewed from a top side, the electrode 20 may have one shapeor mixed shape of a bar shape, a fold line shape, a shape having atleast one curved surface, a polygonal shape, a mixed shape of a curvedsurface and a polygonal shape, a matrix shape, and a shape having anarm.

The electrode 20 having the arm or branch shape may have one of acircular shape, a polygonal shape, and a mixed shape of a curved surfaceand an aspheric surface, but is not limited thereto.

The electrode 20 includes a lower portion 21 and an upper portion 22.The lower portion 21 contacts a top surface of the compoundsemiconductor layer 10, and the upper portion 22 may have a top surfacehaving an area greater than a lower surface of the lower portion 21 onthe lower portion 21. In this case, the upper portion 22 covers a topsurface of the light guide layer 30.

The upper portion 22 of the electrode 20 has a width D2 greater than awidth D1 of the lower surface on the lower portion 21. That is, theelectrode 20 has a top surface width (or area) greater than a lowersurface width (or area). Here, the widths D1, D2, and D3 may be widthsor lengths in the same direction.

In the light guide layer 30, an area of inner surfaces S1 and S3contacting the electrode 20 may be greater by about 30% or more than anarea (or size) of an opened outer surface S2 non-contacting theelectrode 20.

The light guide layer 30 is disposed between a portion of the electrode20 and the compound semiconductor layer 10. The light guide layer 30 isdisposed within a region of the electrode 20 and overlaps the electrode20. Referring to FIG. 2, the light guide layer 30 disposed under theregion of the electrode 20 is expressed as diagonal lines. The electrode20 has at least three outer side surfaces non-contacting the electrode20.

Referring to FIGS. 1 and 2, at least one inner surface of the lightguide layer 30 contacts at least one portion of the lower portion 21 ofthe electrode 20 and a portion of the outer side surfaces may be exposedto the outside.

The light guide layer 30 has a second surface S2 disposed at a sideopposite to the first, second, and third surfaces S1, S2, and S3contacting the lower portion of the electrode 20 and non-contacting thecompound semiconductor layer and a fourth surface S4 contacting the topsurface of the compound semiconductor layer 10.

The second surface S2 of the light guide layer 30 may be a surfaceopposite to the first surface S or a non-contact opened surface exposedto the outside. Thus, light may be emitted from the second surface S2.The second surface S2 of the light guide layer 30 may be disposed on atleast one surface of the electrode 20, e.g., a first side surface, asecond side surface, a third side surface, or all side surfaces. Thus,the second surface S2 of the light guide layer 30 may be one sidesurface or more or three side surfaces as shown in FIG. 2.

The third surface S3 of the light guide layer 30 may contact the lowersurface of the upper portion 22 of the electrode 20. The third surfaceS3 of the light guide layer 30 may be formed parallel to the top surfaceof the electrode 20.

At least one side surface of the second surface S2 of the light guidelayer 30 may protrude from a side surface of the electrode 20 and has adistance of about 1 μm to about 10 μm. The second surface S3 of thelight guide layer 30 may have at least one of an inclined surface, acurved surface, and a flat surface. The second surface S2 of the lightguide layer 30 may have an area greater or less than that of the firstsurface S1.

Here, the inner surfaces S1 and S3 contacting the electrode 20 of aperiphery of the light guide layer 30 may have areas less than orgreater than that of the outer surface S2 non-contacting the electrode20.

The lower surface S4 of the light guide layer 30 may have a flat oruneven surface.

The light guide layer 30 may be formed of a transmittive material suchas nitiride or oxide or a reflective metal containing Ag. The oxide mayinclude one of indium tin oxide (ITO), indium zinc oxide (IZO), indiumzinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), indium galliumzinc oxide (IGZO), indium gallium tin oxide (IGTO), aluminium zinc oxide(AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), ZnO, SiO₂,SiO_(x), Al₂O₃, and TiO_(x), and the nitride may include one of IZONitride (IZON), SiO_(x)N_(y), and Si₃N₄. Since light is transmittedthrough the transmittive oxide and nitride, a portion of light incidentthrough the compound semiconductor layer 10 may refracted ortransmitted. Also, the reflective metal containing Ag may reflect lightincident into an interface with the compound semiconductor layer 10 in adifferent direction to absorb the light or change a critical angle ofthe light. In the current embodiment, a structure guiding light into theinside or guiding the light reflection may be defined as the light guidelayer 30.

The light guide layer 30 may be disposed between the upper portion 22 ofthe electrode 20 and the compound semiconductor layer 10 to reduce acontact area between the electrode 20 and the compound semiconductorlayer 10, thereby extracting light incident into the compoundsemiconductor layer 10 through the light guide layer 30.

Here, current injection efficiency of the electrode 20 is not increasedin proportion to the contact area between the electrode 20 and thecompound semiconductor layer 10. For example, as the contact area isincreased in a specific region, the current injection efficiency orinternal quantum efficiency is not increased in proportion to thecontact area. Also, when the contact area of the electrode 20 isunnecessarily increased, light extraction efficiency may be reduced. Thecurrent injection efficiency of the electrode 20 is further affected bya state in which electrode patterns are distributed.

The electrode 20 contacts a surface of the compound semiconductor layer10, e.g., an N-face. The lower portion 21 of the electrode 20 may haveat least one side contacting the compound semiconductor layer 10 with awidth D1 of less than about 1 μm to about 3 μm. The width D1 may be awidth of the lower surface of the electrode 20 or a width contacting thesemiconductor layer. The width D1 of the lower surface of the electrode20 may be about 10% to about 90% of a width D2 of one side of the topsurface. The electrode 20 may have a thickness of less than aboutseveral μm, e.g., less than 5 μm, but is not limited thereto. Althoughthe top surface of the compound semiconductor layer 10 contacting theelectrode 20 was described as the N-face, the top surface of thecompound semiconductor layer 10 may be a Ga-face. Here, the electrode 20contacts the Ga-face.

A ratio (D1:D3) of the width D1 of the lower surface of the electrode 20to a width D3 of the light guide layer 30 may be about 1:9 to about 9:1.As the width D3 of the light guide layer 30 is increased, lightabsorption by the lower portion 21 may be reduced to improve the lightextraction efficiency. Here, when a pattern width of the electrode 20 issimply narrowed, an operation voltage may be increased. Here, the widthD1 of the lower surface of the electrode 20 may be set in considerationof the operation voltage and the current injection efficiency.

Also, the width D1 of the lower surface of the electrode 20 may be about1/9 to about 9/9 of the width D3 of one side of the light guide layer30. Alternatively, the width D3 of the light guide layer 30 may be about1/9 to about 9/9 of the width D1 of the lower surface of the electrode20.

Referring to FIGS. 1 and 2, when viewed from a top side of a chip, thewidth D2 of the electrode 20, i.e., a line width D2 of the electrode 20may be less than about several tens μm. The light guide layer 30 may beparallel to the lower portion of the electrode 20 in a shape in whichthe light guide layer 30 does not protrude to the outside of theelectrode 20. The light guide layer 30 may have a thickness less thanthat of the electrode 20. An outer surface of the light guide layer 30is flush with at least one side surface of the electrode 20.

Since a lower portion of a side of the electrode 20 overlaps the lightguide layer 30, a portion of light proceeding from the inside of thecompound semiconductor layer 10 to the surface of the compoundsemiconductor layer 10 may be extracted to the outside through the lightguide layer 30 or reflected into the compound semiconductor layer 10.The light guide layer 30 prevents light from being absorbed by theelectrode 20 or guides light to extract the light to the outside.

The electrode structure according to an embodiment includes theelectrode 20 and the light guide layer 30 contacting the top surface ofthe compound semiconductor layer 10. The top surface S3 or lower surfaceS4 of the light guide layer 30 may have an area, which is about 10% toabout 90% of an area of the top surface of the electrode 20.

Also, the light guide layer 30 may buffer an external impact due tobonding applied to a portion of electrode 20.

FIG. 3 is a side-sectional view of an electrode structure on asemiconductor layer according to a second embodiment. In descriptions ofthe second embodiment, the same part as that of the first embodimentwill be described with reference to the first embodiment, and theirduplicated descriptions will be omitted.

Referring to FIG. 3, an electrode 20 is disposed on a compoundsemiconductor layer 10. A light guide layer 31 is disposed between thecompound semiconductor layer 10 and the electrode 20. The light guidelayer 31 has a width D6 (or an area) of a lower surface S4 greater thanthat D5 (or area) of a top surface S3. For example, the light guidelayer 31 may have a polygonal shape such as a trapezoid shape.

Since the width D6 of the lower surface of the light guide layer 31 isfurther widened, an incident area may be increased. Thus, lightextraction efficiency by the light guide layer 31 may be increased.

Since an outer side surface S3 of the light guide layer 30 has an areagreater than that of FIG. 1, the light extraction efficiency may beimproved. Also, a portion of an outer side surface S2 of the light guidelayer 31 may protrude from a side surface of the electrode 20.

FIG. 4 is a side-sectional view of an electrode structure on asemiconductor layer according to a third embodiment. The thirdembodiment will be described with reference to the first embodiment.

Referring to FIG. 4, a light guide layer 30A has a convex lens shape ora hemisphere shape. The light guide layer 30A may be formed of atransmittive material such as oxide or nitride. This refers to the firstembodiment.

The light guide layer 30A contacts a top surface of a compoundsemiconductor layer 10. A contact ratio of the light guide layer 30A andthe compound semiconductor layer 10 refers to the first embodiment.Also, an outer spherical surface S21 of the light guide layer 30A mayhave a wide surface area and a convex lens shape to improve a lightextraction area.

An inside part of the light guide layer 30A overlaps under an electrode20, and an outside part protrudes from the electrode 20. Thus, lightincident through the compound semiconductor layer 10 may be emittedthrough the spherical surface S21 having the lens shape. The light guidelayer 30A may have the hemisphere shape to further buffer an externalimpact due to bonding.

A plurality of light guide layers 30A may be disposed under theelectrode 20. The plurality of guide layer 30A may be disposed on bothlower sides of the electrode 30, but is not limited thereto.

FIG. 5 illustrates a fourth embodiment.

Referring to FIG. 5, a roughness 12 is disposed at a top surface of acompound semiconductor layer 10. The compound semiconductor layer 10 maybe formed of a nitride-based material, and a top surface of the compoundsemiconductor layer 10 may be an N-face. The roughness 12 may be formedinto an uneven pattern having a triangular shape. The roughness 12 mayimprove light extraction efficiency.

A portion of the top surface of the compound semiconductor layer 10 mayhave a flat surface 14. A light guide layer 30 or/and an electrode 20may be disposed on the flat surface 14.

An interface between the compound semiconductor layer 10 and theelectrode 20 may have a rough surface to prevent light from beingabsorbed. For example, when the light guide layer 30 is formed of atransmittive material, the top surface of the compound semiconductorlayer 10 may be flat or rough for incident light. Alternatively, whenthe light guide layer 30 is formed of a reflective material, the topsurface of the compound semiconductor layer 10 may be rough for emittinglight. In this case, a critical angle of light may be changed.

That is, an interface between the light guide layer 20 and the compoundsemiconductor layer 10 may be flat or rough for light transmission orreflection.

FIG. 6 illustrates a fifth embodiment.

Referring to FIG. 6, an electrode 20 of a compound semiconductor layer20 includes a bent part 23 between a lower portion 21 and an upperportion 22. The bent part 23 of the electrode 20 is disposed at a sideopposite to that of a light guide layer 30. The bent part 23 is bentfrom a lower surface of the electrode 20 to extend up to a top surfaceof the electrode 20. The bent part 23 may have a structure in which aside surface between the lower surface and the top surface of theelectrode 20 is stepped.

FIG. 7 illustrates a sixth embodiment.

Referring to FIG. 7, a light guide layer 30B having a multi-layeredstructure is disposed between an electrode 20 and a compoundsemiconductor layer 10. A portion of the electrode 20 overlaps above thelight guide layer 30B. The electrode 20 may be an electrode having a pador arm shape. The light guide layer 30B may be formed of a transmittivematerial or/and a reflective material to improve light extractionefficiency through light transmission or/and reflection.

The light guide layer 30B has a multi-layered structure. A first layer32 may be disposed on the compound semiconductor layer 10 to guideincident light, and a second layer 34 may be disposed on the first layer32 to transmit or reflect the light incident through the first layer 32.The first and second layers 32 and 34 may have the same width andthickness as each other or widths and thicknesses different from eachother.

The first layer 32 may be formed of transmittive oxide, e.g., one ofITO, IZO, IZTO, IAZO, IGZO, IGTO, AZO, ATO, and GZO. The second layer 34may be formed of an insulation material, e.g., one of ZnO, SiO₂,SiO_(x), and Al₂O₃.

Alternatively, the first layer 32 may be a material layer having a firstrefractive index n1 less than that of a nitride semiconductor layer, andthe second layer 34 may be a material layer having a second refractiveindex n2 less than the first refractive index n1. For example, the firstlayer 32 may be formed of ITO, and the second layer 34 may be formed ofSiO₂. Thus, light emitted through the compound semiconductor layer 10may be extracted to the outside through the first layer 32 and thesecond layer 34. Alternatively, the second layer 34 of the light guidelayer 30B may be formed of a reflective material. The reflectivematerial may be a metal containing Al or Ag to reflect light incidentthrough the first layer 32.

FIGS. 8 to 10 illustrate a seventh embodiment.

Referring to FIGS. 8 to 10, an electrode may be disposed on a compoundsemiconductor layer 10, and a light guide layer 30C may be disposedaround a lower portion 21 of the electrode 20A.

The lower portion 21 of the electrode 20A may contact the compoundsemiconductor layer 10 through the inside of the light guide layer 30C.An upper portion 22 of the electrode 20A is disposed on the light guidelayer 30C. The light guide layer 30C may be disposed on both sidesurfaces of the lower portion 21 of the electrode 20A or on all of sidesurfaces. When the light guide layer 30C is disposed around the lowerportion 21 of the electrode 20A, a structure of FIG. 9 may be realized.When the light guide layer 30C is disposed on both sides of the lowerportion 21 of the electrode 20A, a structure of FIG. 10 may be realized.

Here, an inner surface area contacting the electrode 20A of a peripheryof the light guide layer 30C may be less than an outer surface areanon-contacting the electrode 20A.

The lower portion 21 of the electrode 20A contacts the compoundsemiconductor layer 10 through the light guide layer 30C, and the upperportion 22 is disposed on the light guide layer 30C. That is, theelectrode 20A may have a “T” shape in section. Also, an outer side ofthe light guide layer 30C may have a circular or polygonal shape.

FIG. 11 illustrates an eighth embodiment.

Referring to FIG. 11, an electrode layer 40 is disposed on a compoundsemiconductor layer 10. The electrode layer 40 may include atransmittive conductive layer. The electrode layer 40 may have athickness of several hundreds Å or more. The electrode layer 40 may beformed of one of ITO, IZO, IZON, IZTO, IAZO, IGZO, IGTO, AZO, ATO, andGZO.

A light guide layer 30 is disposed on the electrode layer 40. The lightguide layer 30 may be formed of one of ITO, IZO, IZON, IZTO, IAZO, IGZO,IGTO, AZO, ATO, GZO, ZnO, SiO₂, SiO_(x), Al₂O₃, TiO_(x), SiO_(x)N_(y),Si₃N₄, and a reflective metal containing Ag. The light guide layer 30may be formed of the same material as the electrode layer 40 or amaterial different from that of the electrode layer 40.

A portion of the electrode 20 is disposed on the light guide layer 30. Alower portion 21 of the electrode 20 surface-contacts a top surface ofthe compound semiconductor layer 10 through the inside of the electrodelayer 40. Also, the lower portion 21 of the electrode 20 may contact aninner side surface of the electrode layer 40. Also, a portion of theelectrode 20 may further extend up to a top surface of the electrodelayer 40. The electrode layer 40 diffuses a current into an entireregion.

An upper portion 22 of the electrode 20 is disposed on the lower portion21 and the light guide layer 30C.

The electrode layer 40 may cover about 60% to about 95% of the topsurface of the compound semiconductor layer 10, but is not limitedthereto.

Light emitted from the compound semiconductor layer 10 may be extractedthrough the electrode layer 40 and the light guide layer 30.

FIGS. 12 to 21 illustrate a ninth embodiment and a modified example ofan electrode.

Referring to FIG. 12, an electrode 20D including a plurality of armparts 25, 26, and 27 and a light guide layer 30 overlapping underportions of the arm parts 25, 26, and 27 are disposed on a compoundsemiconductor layer 10.

A pad part 24 is disposed on the electrode 20D. The plurality of armparts 25, 26, and 27 is branched from the pad part 24 in center and sidedirections.

A light guide layer 30 (diagonal line region) is disposed under the padpart 24 of the electrode 20D and the plurality of arm parts 25, 26, and27. The light guide layer 30 may be disposed between the electrode 20Dand the compound semiconductor layer 10 to reduce a contact area betweenthe electrode 20D and the compound semiconductor layer 10.

When views from a top side of the device, the light guide layer 30 maybe about 10% to about 90% of an area of a top surface of the electrode20D. Alternatively, a contact area between the light guide layer 30 andthe electrode 20D may be about 10% to about 90% of that between theelectrode 20D and the compound semiconductor layer 10. Thus, the lightguide layer 30 may prevent light from being absorbed by the electrode toimprove light extraction efficiency.

Since the light guide layer 30 reduces the contact area between thecompound semiconductor layer 10 and the electrode 20D, the lightextraction efficiency through a surface of the compound semiconductorlayer 10 may be improved.

Referring to FIG. 13, an electrode 50 is disposed on a portion of anedge of the compound semiconductor layer 10. The electrode 50 includes apad part 54. The electrode 50 may have a side surface inwardly bent froman edge region.

A light guide layer 55 is disposed under the electrode 50. The lightguide layer 55 is disposed under the inside or/and outside of theelectrode 50. The light guide layer 55 effectively guides light emittedfrom the compound semiconductor layer 10.

Referring to FIG. 14, an electrode 60 includes a plurality of arm parts62 radially branched from a pad part 64. A light guide layer 65 has anopened surface under one side and the other side of the electrode 60 andextracts a portion of light incident into the electrode 60 to theoutside.

Referring to FIG. 15, an electrode 70 has a hemisphere shape and apredetermined curvature with respect to a pad part 74. The electrode 70extends up to an edge portion of a compound semiconductor layer 10. Alight guide layer 75 is disposed under the electrode 70. An area of atop surface of the light guide layer 75 may be about 10% to about 90% ofthat of a top surface of the electrode 70. Thus, the light guide layer75 may prevent light from being absorbed by the electrode 70 to improvelight extraction efficiency.

The electrode 70 may uniformly contact the compound semiconductor layer10 with a contact area of about 10% to about 90%.

Referring to FIG. 16, when viewed from a top side, an electrode 80 has apolygonal shape such as a trapezoid shape. One side having a wide areaof the electrode 80 may be disposed in an edge region and used as a padpart 84, and the other side may be used as an arm part 82. A light guidelayer 85 may be disposed under both sides of the electrode 80. A topsurface of the light guide layer 85 may be about 10% to about 90% ofthat of the electrode 80. A lower portion of the electrode 80 may bedisposed between the light guide layers 85 or along a side of the lightguide layer 85.

Referring to FIG. 17, when viewed from a top side, an electrode 90 has alength corresponding to one side of a compound semiconductor layer 10and a predetermined width. A light guide layer 95 partially overlapsunder the outside of the electrode 90. A top surface of the light guidelayer 95 may be about 10% to about 90% of that of the electrode 90.

The electrode 90 has a width gradually narrowed from one side to theother side. The light guide layer 95 may be disposed on both outer sidesof the electrode 90 and have a width gradually narrowed toward the otherside. Here, the electrode 90 may contact the compound semiconductorlayer 10 with a constant width regardless of a variation of the width ofthe light guide layer 95. This may be changed according to embodiments.

Referring to FIG. 18, when viewed from a top side, an electrode 100 hasa triangular shape. A light guide layer 105 partially overlaps under aside of the electrode 100. A lower portion of the electrode 100 contacta top surface of a compound semiconductor layer 10 with a constantwidth.

Referring to FIG. 19, an electrode 110 includes an arm part 114 having aclosed or opened loop shape along a periphery of a top surface of acompound semiconductor layer 10 and a pad part 112 disposed at least onecorner. A light guide layer 115 is disposed under a side of theelectrode 110. The light guide layer 115 may partially overlap a portionof the arm part 114.

Referring to FIG. 20, an electrode 120 includes a side arm part 123having a closed or opened loop shape along a periphery of a top surfaceof a compound semiconductor layer 10, an inner arm part 124 branchedfrom the side arm part 123 in an inward direction, and a pad part 122disposed at least one corner.

A light guide layer 125 is disposed under the outside of the electrode120. The light guide layer 125 may partially overlap along portions ofthe side arm 123 and the inner arm 125. A region overlapping between thelight guide layer 125 and the electrode 120 may be changed according tolight extraction efficiency.

Referring to FIG. 21, an electrode 130 is disposed on at least bothcorners. The electrode 130 includes an arm part 132 and a pad 131. Thelight guide layer 135 overlaps under a portion of the outside of theelectrode 130.

FIG. 22 is a side-sectional view of a light emitting device according toa tenth embodiment. In descriptions of the tenth embodiment, thestructures of the electrode and the light guide layers according to theabove-described embodiments may be selectively applicable.

Referring to FIG. 22, a light emitting device includes a light emittingstructure layer 235, an electrode 220, a light guide layer 225, a firstconductive layer 240, a passivation layer 250, a second conductive layer260, and a support member 270.

The light emitting structure layer may be formed of a Group II to VIcompound semiconductor, e.g., Group III-V compound semiconductor. Forexample, the light emitting structure layer 235 may be formed of asemiconductor material having a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1). For example, the lightemitting structure layer 235 may be formed of at least one selected fromthe group consisting of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN,AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

The light emitting structure layer 235 includes a first conductive typesemiconductor layer 210, an active layer 220, and a second conductivetype semiconductor layer 230. The active layer 220 is disposed betweenthe first conductive type semiconductor layer 210 and the secondconductive type semiconductor layer 230. The light emitting structurelayer 235 may include a third semiconductor layer having a polarityopposite to that of a second conductive type under the second conductivetype semiconductor layer 230. The light emitting structure layer 235 maybe defined as disclosed in the first to ninth embodiments.

The first conductive type semiconductor layer 210 may be realized by atleast one semiconductor layer doped with a first conductive type dopant.For example, the semiconductor layer may be formed a semiconductormaterial having a compositional formula of In_(x)Al_(y)Ga_(1-x-y)N(0≦x≦1, 0≦y≦1, 0≦x+y≦1). For example, the first conductive typesemiconductor layer 210 may be formed of at least one selected from thegroup consisting of GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, AlGaAs,GaP, GaAs, GaAsP, and AlGaInP.

When the first conductive type semiconductor layer 210 is an N-typesemiconductor layer, the first conductive type dopant is an N-typedopant. The N-type dopant may include Si, Ge, Sn, Se, and Te.

An electrode 220 is disposed on a top surface of the first conductivetype semiconductor layer 210. A roughness 212 may be disposed on aportion of the top surface or the entire surface of the first conductivetype semiconductor layer 210. Another semiconductor layer, e.g., anundoped semiconductor layer or a low conductive semiconductor layer,which has a dopant concentration less than that of the first conductivetype semiconductor layer 210, may be disposed between the electrode 220and the first conductive type semiconductor layer 210.

The top surface of the first conductive type semiconductor layer 210 maybe an N-face surface. The electrode 220 contacts the top surface of thefirst conductive type semiconductor layer 210. The electrode 220ohmic-contacts and a portion of the electrode 220 may be used as abonding pad. The electrode 220 may have a single- or multi-layeredstructure. An arm electrode having a line width may be electricallyconnected to the electrode 220.

A contact area between the electrode 220 and the first conductive typesemiconductor layer 210 may be about 10% to about 90% of an area of atop surface of the electrode 220.

The electrode 220 may have a single- or multi-layered structure and beformed of one of Cr, Ti, Al, In, Ta, Pd, Co, Ni, Si, Ge, Ag, Cu, and Auor combinations thereof. The electrode 220 may be formed of one of theforegoing materials in consideration of an ohmic contact, an adhesion, areflective characteristic, and a conductive characteristic with respectto the first conductive type semiconductor layer 210.

When the electrode 220 is the pad, one or plurality of pads may beprovided. The plurality of pads may be electrically connected to eachother. When viewed from a top side, for example, an arm structure of theelectrode 220 includes a linear arm structure, a curved arm structure, amixed structure of the linear arm structure and the curved armstructure, an arm structure branching from one arm structure, apolygonal arm structure, a lattice arm structure, a dot arm structure, alozenge arm structure, a parallelogram arm structure, a mesh armstructure, a stripe arm structure, a cross arm structure, a radial armstructure, a circular arm structure, and a mixed arm structure thereof,but is not limited thereto. The electrode 220 having such an armstructure may smoothly supply a power to the semiconductor layer toprevent current from being concentrated onto one spot.

The electrode 220 includes a lower portion 221 and an upper portion. Thelower portion 221 contacts the top surface of the first conductive typesemiconductor layer 210. The upper portion 222 is disposed on the lowerportion 21 and the light guide layer 225.

The upper portion 222 may have a width greater than that of the lowerportion 221 on the lower portion 221. That is, the electrode 220 has atop surface greater by at least one and half than a lower surfacethereof.

The light guide layer 225 is disposed between the electrode 220 and thefirst conductive type semiconductor layer 210. The light guide layer 225may be formed of a transmittive material such as nitiride or oxide or areflective metal containing Ag. The oxide may include one of ITO, IZO,IZON, IZTO, IAZO, IGZO, IGTO, AZO, ATO, GZO, ZnO, SiO₂, SiO_(x), Al₂O₃,and TiO_(x) or the nitride may include one of SiO_(x)N_(y), and Si₃N₄.Since the oxide and nitride may be defined as transmittive structures,the oxide and nitride may guide incident light to the inside to extractthe light. Also, the reflective material reflects the light from aninterface with the first conductive type semiconductor layer 210 in adifferent direction to prevent the light from being absorbed.

The first conductive type semiconductor layer 225 contacts a lowersurface of the light guide layer 225. A portion of a side surface of thelight guide layer 225 contacts an inner side surface of the electrode220, and a portion of the side surface is exposed to the outside.

The light guide layer 225 is disposed between the electrode 220 and thefirst conductive type semiconductor layer 210 to reduce a contact areabetween the electrode 220 and the first conductive type semiconductorlayer 210.

Here, the contact area between the electrode 220 and the firstconductive type semiconductor layer 210 determines current injectionefficiency. Since the current injection efficiency is not increased inproportion to the contact area between the electrode 220 and the firstconductive type semiconductor layer 210, the increase of the contactarea acts as a factor, which interrupts current extraction efficiency.Thus, the electrode 220 contacts the first conductive type semiconductorlayer 210 within a range in which the current injection efficiency doesnot influence on the contact area between the electrode 220 and thefirst conductive type semiconductor layer 210. The light guide layer 225may be disposed in a region except the contact region. Here, the lightguide layer 225 may be disposed in consideration of an adhesion of theelectrode 220 and the current injection efficiency. The structures ofthe electrode 220 and the light guide layer 225 may be selectivelyapplicable to the disclosed embodiments.

When the electrode 220 includes an N-type semiconductor layer, theelectrode 220 contacts a surface of the first conductive typesemiconductor layer 210, e.g., an N-face. The lower portion 221 that isat least one side of the electrode 220 may contact the first conductivetype semiconductor layer 210 with a width of less than about 3 μm. Also,a width of the lower portion 221 of the electrode 220 may be about 10%to about 90% of that of the upper portion 222.

The electrode 220 may have a thickness of less than about several μm,e.g., less than 5 μm. The light guide layer 225 may have a thicknessless than that of the electrode 220.

A ratio of the lower portion 221 of the electrode 220 to the light guidelayer 225 may be about 1:9. A contact area of the light guide layer 225may be less than the top surface of the electrode 220. For example, thecontact area of the light guide layer 225 may be about 10% to about 90%of the top surface of the electrode 220. Thus, a width of the lowerportion of the electrode 220 may be about 1/9 to about 9/9 of a width ofthe light guide layer 225. Alternatively, the width of the light guidelayer 225 may be about 1/9 to about 9/9 of the width of the lowerportion of the electrode 220.

Here, when viewed from a top side of a chip, the electrode may have awidth, i.e., one line width of less than several tens μm.

When viewed from a top side of the chip, an outer side surface of thelight guide layer 225 includes at least one side surface having a sideopposite to that of the lower portion 221 of the electrode 220 andprotrudes to the outside.

Since the light guide layer 225 partially overlaps under the electrode220, a portion of light proceeding from the inside of the firstconductive type semiconductor layer into a surface may be extracted tothe outside through the light guide layer 225. The light guide layer 225may prevent the light from being absorbed by the electrode 220 toextract the light to the outside.

The active layer 220 is disposed under the first conductive typesemiconductor layer 210. The active layer 220 may have at least one of asingle quantum well structure, a multi quantum well (MQW) structure, aquantum dot structure, and a quantum wire structure. The active layer220 may be formed at a cycle of a well layer/barrier layer using a GroupIII-V compound semiconductor material.

A pair of well layer/barrier layer of the active layer 220 may includeone of an InGaN well layer/GaN barrier layer, a GaN well layer/AlGaNbarrier layer, an InGaN well layer/AlGaN barrier layer, and an InGaNwell layer/InGaN barrier layer. The active layer may have about 3 cyclesto about 30 cycles. At least one barrier layer may be doped with adopant such as indium or silicon or undoped, but is not limited thereto.The barrier layer may have a band gap greater than that of the welllayer.

A conductive type clad layer may be disposed on/under the active layer220. The conductive type clad layer may be formed of a GaN-basedmaterial or/and have a band gap greater than that of the well layer.

A second conductive type semiconductor layer 230 may be disposed underthe active layer 220. The second conductive type semiconductor layer 230may include at least one semiconductor layer, which is doped with asecond conductive type dopant. The semiconductor layer may be formed ofa semiconductor material having a compositional formula ofIn_(x)Al_(y)Ga_(1-x-y)N (0≦x≦1, 0≦y≦1, 0≦x+y≦1). For example, the secondconductive type semiconductor layer 230 may be formed of at least oneselected from the group consisting of GaN, AlN, AlGaN, InGaN, InN,InAlGaN, AlInN, AlGaAs, GaP, GaAs, GaAsP, and AlGaInP.

The second conductive type semiconductor layer 230 may include a P-typesemiconductor layer. The second conductive type dopant may include aP-type dopant such as Mg, Zn, Ca, Sr, or Ba.

A first conductive type semiconductor layer, e.g., an N-typesemiconductor layer may be further disposed on the second conductivetype semiconductor 230. The light emitting structure layer 235 may haveone of an N-P junction structure, a P-N junction structure, an N-P-Njunction structure, and a P-N-P junction structure. Hereinafter, forconvenience of description, a structure in which the second conductivetype semiconductor layer 230 is disposed at the lowermost layer of thelight emitting structure layer 235 will be described as an example.

The light emitting structure layer 235 may have a vertical or inclinedside surface A1 with respect to a lower surface of the second conductivetype semiconductor 230.

The passsivation layer 250 and the first conductive layer 240 aredisposed under the second conductive type semiconductor layer 230.

The passivation layer 250 is disposed around a device. Also, in amanufacturing process, the passivation layer 250 may be disposed in aregion exposed by an isolation etching process, a channel region, or achip boundary portion.

An inside part of the passivation layer 250 is disposed between thesecond conductive type semiconductor layer 230 and the first conductivelayer 240, and an outside part is exposed to the outside than a sidesurface of the light emitting structure layer 235. A lower surface ofthe outside part of the passivation layer 250 may contact a top surfaceof the first conductive layer 240.

The passivation layer 250 may be disposed around a lower surface of thesecond conductive type semiconductor layer 230. The passivation layer250 may be formed of a conductive material or a non-conductive material.When the passivation layer 250 is formed of the conductive material, anoperation voltage may be reduced. Here, the passivation layer 250 may beformed of one of ITO, IZO, IZON, IZTO, IAZO, IGZO, IGTO, AZO, ATO, andGZO.

The passivation layer 250 may be formed of a material havingconductivity less than that of the first conductive layer 240 or thesecond conductive layer 260. The passivation layer 250 may be formed ofa material, which schottky-contacts the second conductive typesemiconductor layer 230, e.g., at least one selected from the groupconsisting of Ti, Ni, Pt, Pd, Rh, Ir, and W. The passivation layer 250may be formed of an insulation material or a conductive oxide material,e.g., one of ITO, IZO, IZON, IZTO, IAZO, IGZO, IGTO, AZO, ATO, GZO,SiO₂, SiO_(x), SiO_(x)N_(y), Si₃N₄, Al₂O₃, and TiO₂.

The passivation layer 250 may be disposed along a periphery of a lowerportion of the second conductive type semiconductor layer 230 in apredetermined shape such as a polygonal shape, a circular shape, or arandom shape. Also, the passivation layer 250 may have one of a frameshape, a ring shape, and a loop shape.

For example, when the passivation layer 250 is formed of alight-transmitting material such as ITO, a laser is transmitted in anisolation etching process. Thus, the outside of the light emittingstructure layer 235 does not have an influence on an electric effect toimprove electrical characteristics, thereby improving light emittingefficiency.

The passivation layer 250 may space the second conductive layer 260 fromthe light emitting structure layer 235. Also, the passivation layer 250may improve an adhesion of the second conductive type semiconductorlayer 230.

The first conductive layer 240 may include an ohmic layer or/and areflective layer. The ohmic layer ohmic-contacts a lower portion of thesecond conductive type semiconductor layer 230. The ohmic layer may beformed of one of ITO, IZO, IZON, IZTO, IAZO, IGZO, IGTO, AZO, ATO, GZO,and a metal such as Ni or Ag. The reflective layer may include at leastone layer formed of one of metals having a reflectance of about 50% ormore, e.g., one of Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and Hf.

The first conductive layer 240 may reflect light incident into the lightemitting structure layer 235 through the reflective metal to improvelight extraction efficiency.

At least one of the first conductive layer 240 and the second conductivelayer 260 may extend under the passivation layer 250.

The second conductive layer 260 may be formed as a barrier layer or abonding layer under the first conductive layer 240. The secondconductive layer 260 may be formed of at least one selected from thegroup consisting of Ti, Au, Sn, Ni, Cr, Ga, In, Bi, Cu, Ag, and Ta.

The support member 270 may be disposed under the second conductive layer260. The support member 270 may be formed of a conductive material,e.g., copper, gold, or a carrier wafer such as Si, Ge, GaAs, ZnO, SiC,and SiGe. The support member 270 may not be provided or have a single-or two-layered structure according to a thickness or strength thereof.Alternatively, the support member 270 may be realized by a conductivesheet or an insulation material.

In a process of manufacturing the light emitting device 20, a firstconductive type semiconductor layer 210, an active layer 220, and asecond conductive semiconductor layer 230 are grown on a growthsubstrate (not shown). Then, a passivation layer 250, a first conductivelayer 240, a second conductive layer 260, and a conductive supportmember 270 are formed on the second conductive type semiconductor layer230. Thereafter, the growth substrate may be removed by a physicalmethod (e.g., laser lift off) or/and a chemical method (wet etching). Alight guide layer 225 and an electrode 220 are formed before or after anisolation etching process is performed to separate the substrate into aunit chip. The process is not limited to the embodiments.

FIG. 23 is a side-sectional view of a light emitting device according toan eleventh embodiment. In descriptions of the eleventh embodiment, thesame part as that of the tenth embodiment will be described withreference to the tenth embodiment, and their duplicated descriptionswill be omitted.

Referring to FIG. 23, a light emitting device 202 has a roughness 212 ona portion of a top surface of a first conductive type semiconductorlayer 210. The roughness 212 may extend up to a lower surface of anelectrode 220. A flat surface, but the roughness 212, may be disposed ona surface S5 contacting a light guide layer 225. Thus, light may beincident into the flat surface S5 of the light guide layer 225 toimprove light extraction efficiency. Also, the roughness 212 disposedunder the electrode 220 may prevent light from being absorbed.

FIG. 24 is a side-sectional view of a light emitting device according toa twelfth embodiment. In descriptions of the twelfth embodiment, thesame part as that of the tenth embodiment will be described withreference to the tenth embodiment, and their duplicated descriptionswill be omitted.

Referring to FIG. 24, a light emitting device 203 may include a currentblocking layer 245 at a position corresponding to that of an electrode220. The current blocking layer 245 may be disposed between a firstconductive layer 240 and the second conductive type semiconductor layer230.

The current blocking layer 245 may be formed of a material havingconductivity less than that of the first conductive layer 240 or thesecond conductive layer 260, for example, at least one selected from thegroup consisting of ITO, IZON, IZTO, IAZO, IGZO, IGTO, AZO, ATO, GZO,ZnO, SiO₂, SiO_(x), SiO_(x)N_(y), Si₃N₄, Al₂O₃, TiO₂, Ti, Al, and Cr.

Here, when the first conductive layer 240 is formed of ITO, the currentblocking layer 245 may be formed of an insulation material such as ZnOor SiO₂.

The current blocking layer 245 may overlap a position corresponding tothat of a pattern of the electrode 220, i.e., a position correspondingto a lower portion 221 of the electrode 220. Alternatively, the currentblocking layer 245 may be disposed inside the first conductive typesemiconductor layer 210. The current blocking layer may be disposed in aregion corresponding to the lower portion 221 of the electrode 220.

FIG. 25 is a side-sectional view of a light emitting device according toa thirteenth embodiment. In descriptions of the thirteenth embodiment,the same part as that of the tenth embodiment will be described withreference to the tenth embodiment, and their duplicated descriptionswill be omitted.

Referring to FIG. 25, a light emitting device 204 includes an N-P-N orP-N-P type light emitting structure layer 235A. The light emittingstructure layer 235A includes a first conductive type semiconductorlayer 210, an active layer 220 under the first conductive typesemiconductor layer 210, a second conductive type semiconductor layer230 under the active layer 230, and a third conductive typesemiconductor layer 232 under the second conductive type semiconductorlayer 230.

When the first conductive type semiconductor layer 210 and the thirdconductive type semiconductor layer 230 include an N-type semiconductorlayer, the second conductive type semiconductor layer 230 may include aP-type semiconductor layer, and vice versa.

A first conductive layer 240A is disposed under the inside of the thirdconductive type semiconductor layer 232, and a passivation layer 250 isdisposed around a lower portion of the third conductive typesemiconductor layer 232.

The second conductive layer 260 is disposed under the passivation 250and the first conductive layer 240A. A conductive support member 270 isdisposed under the second conductive layer 260. Since the firstconductive layer 240A contacts only the third conductive typesemiconductor layer 232, it may prevent the first conductive layer 240Afrom being laminated.

FIG. 26 is a side-sectional view of a light emitting device according toa fourteenth embodiment. In descriptions of the fourteenth embodiment,the same part as that of the tenth embodiment will be described withreference to the tenth embodiment, and their duplicated descriptionswill be omitted.

Referring to FIG. 26, a light emitting device 205 has a structure inwhich an insulation layer 280 is disposed around a light emitting layer235.

The insulation layer 280 may be formed of at least one selected from thegroup consisting of SiO₂, SiO_(x), SiO_(x)N_(y), Si₃N₄, Al₂O₃, and TiO₂.Since an upper end of the insulation layer 280 covers a periphery of atop surface of a first conductive type semiconductor layer 210, a lowerend of the insulation layer 280 is disposed on a passivation layer 250.Thus, the insulation layer 280 may prevent an interlayer short fromoccurring on a periphery of the light emitting structure layer 235.Here, the insulation layer 280 may be formed of the same material as alight guide layer 225 and using the same process as that of the lightguide layer 225.

The light emitting device according to the first to fourteenthembodiments may be packaged on a semiconductor layer formed of a resinmaterial or silicon, an insulation substrate, or a ceramic substrate.Also, the light emitting device may be used as light sources for anindicating device, a lighting device, and a display device.

FIG. 27 is a side-sectional view of a light emitting device packageaccording to a fifteenth embodiment.

Referring to FIG. 27, a light emitting device package 500 includes abody 511, first and second lead electrodes 512 and 512 disposed on thebody 511, a light emitting device 200 according to an embodiment, whichis disposed on the body 511 and electrically connected to the first andsecond lead electrodes 512 and 513, and a molding member 517 surroundingthe light emitting device 200.

The body 511 may be formed of a silicon material, a synthetic resinmaterial, or a metal material. The body 511 has an upwardly openedcavity structure, and an inclined surface may be disposed around thelight emitting device 200.

The first lead electrode 512 and the second lead electrode 513 areelectrically separated from each other. The first and second leadelectrodes 512 and 513 provide a power to the light emitting device 200.Also, the first and second lead electrodes 512 and 513 may reflect lightemitted from the light emitting device 200 to improve light efficiencyand discharge heat generated in the light emitting device 200 to theoutside. Each of the first and second lead electrodes 512 and 513 mayinclude at least one of a lead frame structure, a through holestructure, and a plating layer.

The light emitting device 200 may be disposed on the body 511 or thefirst or second lead electrode 512 or 513

The light emitting device 200 may be electrically connected to the firstlead electrode 512 through a wire and electrically connected to thesecond lead electrode 513 through die-bonding.

The molding member 517 may surround the light emitting device 200 toprotect the light emitting device 200. Also, a phosphor may be containedin the molding member 517 to change a wavelength of light emitted fromthe light emitting device 200.

<Lighting System>

The semiconductor light emitting device or a light emitting devicepackage according to an embodiment may be provided in plurality. Theplurality of light emitting devices or the light emitting devicepackages may be arrayed on the substrate. Optical members such as alight guide plate, a prism sheet, and a diffusion sheet may be disposedon a path of the light emitted from the light emitting device. The lightemitting device package, the substrate, and the optical members mayserve as a lighting unit. The lighting unit may be manufactured in a topview type or a side view type. Thus, the lighting unit may be providedas display devices for a portable terminal, a notebook computer, etc, orvariously applied to the lighting device, the indicating device, etc.Also, in another embodiment, the lighting unit may be realized as alighting system including the light emitting device or the lightemitting device package according to the above-described embodiments.The lighting system may include display devices illustrated in FIGS. 28and 29, a lighting device illustrated in FIG. 30, illumination lamps,signal lights, car headlights, electronic displays, and the like.

FIG. 28 is an exploded perspective view illustrating a display deviceaccording to an embodiment.

Referring to FIG. 28, a display device 1000 according to the embodimentmay include a light guide plate 1041, a light emitting module 1031providing light to the light guide plate 1041, a reflection member 1022under the light guide plate 1041, an optical sheet 1051 on the lightguide plate 1041, a display panel 1061 on the optical sheet 1051, and abottom cover 1011 storing the light guide 1041, the light emittingmodule 1031, and the reflection member 1022; however, it is not limitedto this.

The bottom cover 1011, the reflection sheet 1022, the light guide plate1041, and the optical sheet 1051 may be defined as a light unit 1050.

The light guide plate 1041 serves to diffuse light for convergence to asurface light source. The light guide plate 1041 is formed withtransparent material and, e.g., may include one of acrylic resin such aspolymethyl metaacrylate (PMMA), polyethylene terephthlate (PET), polycarbonate (PC), cycloolefin copolymer (COC), and polyethylenenaphthalate (PEN) resins.

The light emitting module 1031 provides light to at least one side ofthe light guide plate 1041 and ultimately acts as a light source of thedisplay device.

At least one light emitting module 1031 is included, and it may providelight directly or indirectly at one side of the light guide plate 1041.The light emitting module 1031 includes a substrate 1033 and the lightemitting device package 500 according to the above-disclosed embodiment.The light emitting device package 500 may be arrayed at predeterminedintervals on the substrate 1033.

The substrate 1033 may be a Printed Circuit Board (PCB) including acircuit pattern (not illustrated). However, the substrate 1033 mayinclude not only the typical PCB but also a metal core PCB (MCPCB) and aflexible PCB (FPCB), and it is not limited to this. In the case that thelight emitting device package 500 is installed on the side of the bottomcover 1011 or on a heat radiating plate, the substrate 1033 may beeliminated. Herein, a part of the heat radiating plate may be contactedto an upper surface of the bottom cover 1011.

The plurality of light emitting device packages 500 may be installed onthe substrate 1033 so that a light-emitting surface is separated fromthe light guide plate 1041 by a predetermined distance, and there is nolimit for this. The light emitting device package 500 may provide lightto a light-entering part, i.e., one side, of the light guide plate 1041directly or indirectly, and there is no limit for this.

The reflection member 1022 may be disposed under the light guide plate1041. The reflection member 1022 reflects the light incident to thelower surface of the light guide plate 1041 in an upward direction sothat brightness of the light unit 1050 may be improved. The reflectionmember 1022 may be formed with, e.g., PET (Polyethylene terephthalate),PC, PVC (polyvinyl chloride) resins; however, it is not limited to this.The reflection member 1022 may be the upper surface of the bottom cover1011; however, there is no limit for this.

The bottom cover 1011 may store the light guide plate 1041, the lightemitting module 1031, and the reflection member 1022. To this end, thebottom cover 1011 may be provided with a storing unit 1012 having ashape of a box whose upper surface is open, and there is not limit forthis. The bottom cover 1011 may be combined with a top cover, and thereis no limit for this.

The bottom cover 1011 may be formed with metal material or resinmaterial and may be fabricated using processes of press or extrusionmolding. The bottom cover 1011 may also include metal or non-metalmaterial having good thermal conductivity, and there is no limit forthis.

The display panel 1061 is, e.g., an LCD panel, and includes transparentfirst and second substrates, and a liquid crystal layer between thefirst and second substrates. On at least one side of the display panel1061, a polarizing plate may be attached; however, the attachingstructure is not limited to this. The display panel 1061 displaysinformation by the light which passes through the optical sheet 1051.The display device 1000 may be applied to various cell phones, monitorsof notebook computers, monitors of laptop computers, and televisions.

The optical sheet 1051 is disposed between the display panel 1061 andthe light guide plate 1041 and includes at least one translucent sheet.The optical sheet 1051 may include at least one of, e.g., diffusionsheet, horizontal and vertical prism sheets, and brightness enhancementsheet. The diffusion sheet diffuses the incident light. The horizontalor/and vertical prism sheet concentrates the incident light to a displayregion. The brightness enhancement sheet reuses lost light to enhancebrightness. A protection sheet may be disposed on the display panel1061, and there is no limit for this.

Herein, on the light path of the light emitting module 1031, the lightguide plate 1041 and the optical sheet 1051 may be included as opticalmembers; however, there is no limit for this.

FIG. 29 is a diagram illustrating a display device according to anembodiment.

Referring to FIG. 29, a display device 1100 includes a bottom cover1152, a substrate 1120, an optical member 1154, and a display panel1155. Herein, the above-disclosed light emitting device packages 500 arearrayed on the substrate 1120.

The substrate 1120 and the light emitting device package 500 may bedefined as a light emitting module 1060. The bottom cover 1152, at leastone light emitting module 1060, and the optical member 1154 may bedefined as a light unit.

The bottom cover 1152 may be provided with a storing unit 1153, andthere is no limit for this.

Herein, the optical member 1154 may includes at least one of the lens,light guide plate, diffusion sheet, horizontal and vertical prismsheets, and brightness enhancement sheet. The light guide plate may beformed with PC material or polymethyl metaacrylate (PMMA) material, andthis light guide plate may be eliminated. The diffusion sheet diffusesthe incident light. The horizontal or/and vertical prism sheetconcentrates the incident light to the display region. The brightnessenhancement sheet reuses lost light to enhance brightness.

The optical member 1154 is disposed on the light emitting module 1060.The optical member 1154 converts the light emitted from the lightemitting module 1060 to the surface light source, or performs diffusingand concentrating light.

FIG. 30 is a perspective view illustrating an lighting device accordingto an embodiment.

Referring to FIG. 30, an illumination device 1500 may include a case1510, a light emitting module 1530 installed to the case 1510, and aconnection terminal 1520 installed to the case 1510 and provided withpower from an external power source.

It is preferable to form the case 1510 with material which has good heatradiation characteristics. For instance, the case 1510 may be formedwith metal material or resin material.

The light emitting module 1530 may include a substrate 1532 and thelight emitting device package 500 according to the embodiment installedon the substrate 1532. The plurality of light emitting device packages500 may be arrayed in a matrix form or may be arrayed being separatedfrom each other at predetermined intervals.

The substrate 1532 may be an insulator where a circuit pattern isprinted. For instance, the substrate 1532 may include the PCB, metalcore PCB, flexible PCB, ceramic PCB, and FR-4 substrate.

The substrate 1532 may also be formed with material which efficientlyreflects light, or its surface may be coated with color, e.g., white andsilver, which efficiently reflects light.

At least one light emitting device package 500 may be installed on thesubstrate 1532. Each of the light emitting device packages 500 mayinclude at least one Light Emitting Diode (LED) chip. The LED chip mayinclude a light emitting diode of visible light such as red, green,blue, or white or a UV light emitting diode which emits Ultra Violet(UV).

A combination of various light emitting device packages 500 may bedisposed in the light emitting module 1530 for obtaining color tone andbrightness. For instance, for securing high Color Rendering Index (CRI),a white light emitting diode, a red light emitting diode, and a greenlight emitting diode may be combined and disposed.

The connection terminal 1520 may be electrically connected to the lightemitting module 1530 to supply power. The connection terminal 1520 isscrewed to be connected to the external power source in a socket method;however, there is no limit for this. For instance, the connectionterminal 1520 may be formed as a pin shape to be inserted into theexternal power source or may be connected to the external power sourceby a wire.

The light emitting device according to the embodiment(s) may be packagedonto a semiconductor substrate formed of a resin material or silicon, aninsulation substrate, or a ceramic substrate and used as light sourcesfor an indicating device, a lighting device, and a display device. Also,each of the foregoing embodiments may not be limited to each ofembodiments and applied to the foregoing other embodiments, but are notlimited thereto.

The light emitting device or the light emitting device package accordingto the embodiments may be applicable to a lighting system. The lightingsystem may include a structure in which the plurality of light emittingdevices or the plurality of light emitting device packages is arrayed.

According to the embodiments, the light extraction efficiency may beimproved in the light emitting device. Also, the contact region of theelectrode may be reduced on the surface of the semiconductor layer toimprove the light extraction efficiency on the surface of thesemiconductor layer.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A light emitting device comprising: a conductivelayer; an electrode; a light emitting structure layer disposed betweenthe electrode and the conductive layer, and the light emitting structurelayer including a first semiconductor layer, a second semiconductorlayer under the first semiconductor layer, and an active layer betweenthe first semiconductor layer and the second semiconductor layer; and alight guide layer including a transmittive material between the firstsemiconductor layer and the electrode, wherein the electrode includes afirst portion contacting at least one side surface of the light guidelayer and a second portion extending from the first portion toward a topsurface of the light guide layer, wherein a width of a lower surface ofthe light guide layer is less than a width of a top surface of the firstsemiconductor layer, wherein an entire top surface of the light guidelayer contacts a lower surface of the second portion of the electrode,wherein the entire top surface of the light guide layer has a smallerarea than a top surface of the electrode, wherein the light guide layerincludes a first part and a second part opposite to the first part,wherein the first portion of the electrode is disposed between the firstpart of the light guide layer and the second part of the light guidelayer, wherein the first part of the light guide layer includes a firstside surface that contacts the first portion of the electrode and asecond side surface that does not contact the electrode, wherein thesecond part of the light guide layer includes a third side surface thatcontacts the first portion of the electrode and a fourth side surfacethat does not contact the electrode, and wherein the second side surfaceof the first part is disposed in opposing relation to the fourth sidesurface of the second part.
 2. The light emitting device of claim 1,wherein the second side surface of the light guide layer has an areagreater than the first side surface.
 3. The light emitting device ofclaim 1, wherein the second side surface of the light guide layer isflush with at least one side surface of the electrode, and the lightguide layer is disposed within a region of the electrode.
 4. The lightemitting device of claim 1, wherein a portion of the second side surfaceof the light guide layer has a curved surface or is inclined withrespect to the lower surface of the light guide layer.
 5. The lightemitting device of claim 1, wherein a size of the lower surface of thelight guide layer is greater than a size of the top surface of the lightguide layer.
 6. The light emitting device of claim 1, wherein a size ofthe lower surface of the light guide layer is about 10% to about 90% ofa size of a top surface of the electrode.
 7. The light emitting deviceof claim 1, wherein a thickness of the light guide layer is less than athickness of the electrode, and a width of the light guide layer in afirst direction is less than a width of the electrode in the firstdirection.
 8. The light emitting device of claim 6, wherein a lowersurface of the electrode contacts the top surface of the firstsemiconductor layer, and a size of the lower surface of the electrode isabout 10% to about 90% of a size of the top surface of the electrode. 9.The light emitting device of claim 1, wherein a lower surface of theelectrode contacts a top surface of an N-face of the first semiconductorlayer, and a side of a lower surface of the electrode has a width ofabout 1 μm to about 3 μm.
 10. The light emitting device of claim 1,wherein the second side surface of the light guide layer protrudes byabout 1 μm to about 10 μm from a side surface of the electrodeapproaching the outer surface of the light guide layer.
 11. The lightemitting device of claim 1, wherein the light guide layer is formed ofat least one of a transmittive oxide material, a transmittive nitridematerial, and an insulation material
 12. A light emitting devicecomprising: a light emitting structure layer including a firstsemiconductor layer, a second semiconductor layer under the firstsemiconductor layer, and an active layer between the first semiconductorlayer and the second semiconductor layer; an electrode contacting a topsurface of the first semiconductor layer; a light guide layer includinga transmittive material between the electrode and the firstsemiconductor layer; a transmittive electrode layer between theelectrode and the light guide layer; and a plurality of conductivelayers under the second semiconductor layer, wherein the electrodeincludes a first portion contacting at least one side surface of thelight guide layer and a second portion extending from the first portiontoward a top surface of the light guide layer, wherein a width of thelight guide layer is smaller than a width of a top surface of the firstsemiconductor layer, wherein an entire top surface of the light guidelayer contacts a lower surface of the second portion of the electrode,wherein the entire top surface of the light guide layer has a smallerarea than a top surface of the electrode, wherein the light guide layerincludes a first part and a second part opposite to the first part,wherein the first portion of the electrode is disposed between the firstpart of the light guide layer and the second part of the light guidelayer, wherein the first part of the light guide layer includes a firstside surface that contacts the first portion of the electrode and asecond side surface that does not contact the electrode, wherein thesecond part of the light guide layer includes a third side surface thatcontacts the first portion of the electrode and a fourth side surfacethat does not contact the electrode, and wherein the second side surfaceof the first part is disposed in opposing relation to the fourth sidesurface of the second part.
 13. The light emitting device of claim 12,wherein the electrode comprises a pad part and at least one arm partextending from the pad part, wherein the light guide layer is disposedunder regions of at least one of the pad part and the arm part.
 14. Thelight emitting device of claim 12, wherein the first semiconductor layercomprises an N-type semiconductor layer, and the top surface of thefirst semiconductor layer is an N-face and contacts the electrode andthe light guide layer.
 15. The light emitting device of claim 12,wherein the light guide layer comprises a first layer having a firstrefractive index between the first semiconductor layer and theelectrode, and a second layer having a second refractive index that isless than the first refractive index of the first layer between thefirst layer and the electrode.
 16. The light emitting device of claim12, wherein the light guide layer is formed of at least one selectedfrom the group consisting of ITO(indium tin oxide), IZO(indium zincoxide), IZTO(indium zinc tin oxide), IAZO(indium aluminum zinc oxide),IGZO(indium gallium zinc oxide), IGTO(indium gallium tin oxide),AZO(aluminum zinc oxide), ATO(antimony tin oxide), GZO(gallium zincoxide), ZnO, SiO₂, SiO_(x), SiO_(x)N_(y), Si₃N₄, Al₂O₃, or TiO₂.
 17. Thelight emitting device of claim 12, wherein the transmittive electrodelayer extends to outside from the region of the electrode, wherein theelectrode contacts the transmittive electrode layer and the top surfaceof the first semiconductor layer.
 18. The light emitting device of claim12, wherein a portion of the top surface of the first semiconductorlayer comprises a roughness, and at least one of the electrode and thelight guide layer is disposed on the roughness.
 19. The light emittingdevice of claim 1, wherein the first part of the light guide layerdirectly contacts the second part of the light guide layer.
 20. Thelight emitting device of claim 1, wherein the light guide layercomprises a first layer between the first semiconductor layer and theelectrode and a second layer between the first layer and the electrode,wherein the first layer is formed of a light-transmittive material,wherein the second layer is formed of a conductive metal, wherein a topsurface of the first layer directly contacts a lower surface of thesecond layer.